Pneumatic tires, while common in general public use, have proven to be insufficient for certain off-road conditions. Rough terrain and difficult working environments such as scrap yards, steel mills, waste disposal sites, and logging operations, to name just a few, require more durable and wear resistant tires than can be provided by pneumatic tires which rely on the integrity of the pneumatic chamber for rideability. Consequently, developments have been made in the area of solid tires which are more durable in such off road applications which would otherwise be likely to puncture pneumatic tires.
There are a wide variety of machines and manufacturers which produce off-the-road machinery and vehicles. Unfortunately, there are also a wide variety of hub and axle configurations each with its own bolt spacing and bolt circle diameter. To be able to mount their tires on such machines, tire manufacturers must provide rims which match these various hub-bolt configurations. This has resulted tire manufacturers having to make specific tire rims, unique to particular configurations for each make of machine, making the manufacture of such tires less efficient and more expensive.
Prior efforts to deal with this problem have thus far been unsatisfactory. Attempts have been made to provide a rim assembly which is, to a limited degree, adaptable to different bolt configurations. For example, two prior Canadian patents, 886,468, dated Nov. 23, 1971 and titled Automotive Wheel Structure and No. 981,312, dated Jan. 6, 1976 and titled Custom Wheel Assembly, disclose inventions which attempt to deal with this problem.
The 886,468 patent teaches a rim having holes of a larger diameter than necessary to accommodate the hub bolts, which larger diameter is to accommodate varying bolt circle configurations. The rim is placed over the bolts on the hub. The gaps that are left by reason of the over size holes are then filled in by special adapter bosses. However, this invention requires a plurality of special bosses, one for each bolt of the hub and thus is expensive and difficult to use.
The invention of the 981,312 patent is similar in that it teaches a rim having radial slots to allow for variation in the bolt circle diameter. A cover plate is also provided that has a series of holes positioned to conform with the different placements of the bolts in different diameter bolt circles. The cover plate is fastened tightly over the bolts and by being tightly fastened down onto the rim prevents the rim from sliding relative to the bolts located in the slots in the rim. However, this is expensive and is of limited adaptability due to the radial nature of its slots.
Further, both of these patents are directed at the decorative wheels in the automobile industry. As there are only three primary bolt circle diameters in the automotive field, both inventions only comprehend variations for the three standard types. Furthermore, they do not provide for any changes in the number of bolts or variability in the angular spacing between them. To provide a wheel for a hub whose bolt circle diameter is not one of the three standard or whose number of bolts is different, a completely unique rim would be required. Thus their scope of actual adaptability is very narrow.
It is desirable to decrease the number of unique rims and thus reduce costs of manufacture. It is also desirable to promote greater flexibility for a given tire in that an owner may be able to use it on a number of different vehicles thus extending its useful life. What is also desired is a means by which tire rims can be universally adaptable to the bolt spacing for hubs of the various machines that are presently being made by different domestic and foreign industrial equipment manufacturers.